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Rearranged code, added comments.

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This commit is contained in:
Stephen Marz 2020-04-26 08:43:03 -04:00
parent 42c14bf930
commit cc3b78973c
1 changed files with 174 additions and 166 deletions
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340
risc_v/src/test.rs
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@ -20,6 +20,178 @@ use crate::{cpu::{build_satp,
use crate::elf; use crate::elf;
use crate::fs::BlockBuffer; use crate::fs::BlockBuffer;
/// Test block will load raw binaries into memory to execute them. This function
/// will load ELF files and try to execute them.
pub fn test_elf() {
// The bytes to read would usually come from the inode, but we are in an
// interrupt context right now, so we cannot pause. Usually, this would be done
// by an exec system call.
let files_inode = 25u32;
let files_size = 14304;
let bytes_to_read = 1024 * 50;
let mut buffer = BlockBuffer::new(bytes_to_read);
// Read the file from the disk. I got the inode by mounting
// the harddrive as a loop on Linux and stat'ing the inode.
let bytes_read = syscall_fs_read(8, files_inode, buffer.get_mut(), bytes_to_read as u32, 0);
// After compiling our program, I manually looked and saw it was 18,360
// bytes. So, to make sure we got the right one, I do a manual check
// here.
if bytes_read != files_size {
println!(
"Unable to load program at inode {}, which should be \
{} bytes, got {}",
files_inode,
files_size,
bytes_read
);
return;
}
// Let's get this program running!
// Everything is "page" based since we're going to map pages to
// user space. So, we need to know how many program pages we
// need. Each page is 4096 bytes.
let program_pages = (bytes_read / PAGE_SIZE) + 1;
let my_pid = unsafe { NEXT_PID + 1 };
let elf_hdr;
unsafe {
NEXT_PID += 1;
// Load the ELF
elf_hdr = (buffer.get() as *const elf::Header).as_ref().unwrap();
}
if elf_hdr.magic != elf::MAGIC {
println!("ELF magic didn't match.");
return;
}
if elf_hdr.machine != elf::MACHINE_RISCV {
println!("ELF loaded is not RISC-V.");
return;
}
if elf_hdr.obj_type != elf::TYPE_EXEC {
println!("ELF is not an executable.");
return;
}
let mut my_proc =
Process { frame: zalloc(1) as *mut TrapFrame,
stack: zalloc(STACK_PAGES),
pid: my_pid,
root: zalloc(1) as *mut Table,
state: ProcessState::Running,
data: ProcessData::zero(),
sleep_until: 0,
program: zalloc(program_pages), };
// Map the program in the MMU.
let ptr = my_proc.program;
let table = unsafe { my_proc.root.as_mut().unwrap() };
unsafe {
let ph_tab = buffer.get().add(elf_hdr.phoff) as *const elf::ProgramHeader;
for i in 0..elf_hdr.phnum as usize {
let ph = ph_tab.add(i).as_ref().unwrap();
if ph.seg_type != elf::PH_SEG_TYPE_LOAD {
continue;
}
if ph.memsz == 0 {
continue;
}
memcpy(ptr.add(ph.off), buffer.get().add(ph.off), ph.memsz);
let mut bits = EntryBits::User.val();
// This sucks, but we check each bit in the flags to see if
// we need to add it to the PH permissions.
if ph.flags & elf::PROG_EXECUTE != 0 {
bits |= EntryBits::Execute.val();
}
if ph.flags & elf::PROG_READ != 0 {
bits |= EntryBits::Read.val();
}
if ph.flags & elf::PROG_WRITE != 0 {
bits |= EntryBits::Write.val();
}
// Now we map the program counter. The virtual address is provided
// in the ELF program header.
let pages = (ph.memsz + PAGE_SIZE) / PAGE_SIZE;
for i in 0..pages {
let vaddr = ph.vaddr + i * PAGE_SIZE;
// The ELF specifies a paddr, but not when we use the vaddr!
let paddr = ptr as usize + i * PAGE_SIZE;
map(
table,
vaddr,
paddr,
bits,
0,
);
}
}
}
// This will map all of the program pages. Notice that in linker.lds in userspace
// we set the entry point address to 0x2000_0000. This is the same address as
// PROCESS_STARTING_ADDR, and they must match.
// Map the stack
let ptr = my_proc.stack as *mut u8;
for i in 0..STACK_PAGES {
let vaddr = STACK_ADDR + i * PAGE_SIZE;
let paddr = ptr as usize + i * PAGE_SIZE;
// We create the stack. We don't load a stack from the disk. This is why I don't
// need to make the stack executable.
map(
table,
vaddr,
paddr,
EntryBits::UserReadWrite.val(),
0,
);
}
// Set everything up in the trap frame
unsafe {
// The program counter is a virtual memory address and is loaded into mepc
// when we execute mret.
(*my_proc.frame).pc = elf_hdr.entry_addr;
// Stack pointer. The stack starts at the bottom and works its way up, so we have to
// set the stack pointer to the bottom.
(*my_proc.frame).regs[2] =
STACK_ADDR as usize + STACK_PAGES * PAGE_SIZE;
// USER MODE! This is how we set what'll go into mstatus when we run the process.
(*my_proc.frame).mode = CpuMode::User as usize;
(*my_proc.frame).pid = my_proc.pid as usize;
// The SATP register is used for the MMU, so we need to
// map our table into that register. The switch_to_user
// function will load .satp into the actual register
// when the time comes.
(*my_proc.frame).satp =
build_satp(
SatpMode::Sv39,
my_proc.pid as usize,
my_proc.root as usize,
);
}
// The ASID field of the SATP register is only 16-bits, and we reserved
// 0 for the kernel, even though we run the kernel in machine mode for now.
// Since we don't reuse PIDs, this means that we can only spawn 65534 processes.
satp_fence_asid(my_pid as usize);
// I took a different tact here than in process.rs. In there I created the process
// while holding onto the process list. It doesn't really matter since this is synchronous,
// but it might get dicey
if let Some(mut pl) = unsafe { PROCESS_LIST.take() } {
// As soon as we push this process on the list, it'll be schedule-able.
println!(
"Added user process to the scheduler...get \
ready for take-off!"
);
pl.push_back(my_proc);
unsafe {
PROCESS_LIST.replace(pl);
}
}
else {
println!("Unable to spawn process.");
// Since my_proc couldn't enter the process list, it
// will be dropped and all of the associated allocations
// will be deallocated.
}
println!();
}
/// This is no longer relevant. It was used to test reading, loading, and
/// executing flat binaries.
pub fn test_block() { pub fn test_block() {
// The bytes to read would usually come from the inode, but we are in an // The bytes to read would usually come from the inode, but we are in an
// interrupt context right now, so we cannot pause. Usually, this would be done // interrupt context right now, so we cannot pause. Usually, this would be done
@ -148,170 +320,6 @@ pub fn test_block() {
kfree(buffer); kfree(buffer);
} }
/// Test block will load raw binaries into memory to execute them. This function
/// will load ELF files and try to execute them.
pub fn test_elf() {
// The bytes to read would usually come from the inode, but we are in an
// interrupt context right now, so we cannot pause. Usually, this would be done
// by an exec system call.
let files_inode = 25u32;
let files_size = 14304;
let bytes_to_read = 1024 * 50;
let mut buffer = BlockBuffer::new(bytes_to_read);
// Read the file from the disk. I got the inode by mounting
// the harddrive as a loop on Linux and stat'ing the inode.
let bytes_read = syscall_fs_read(8, files_inode, buffer.get_mut(), bytes_to_read as u32, 0);
// After compiling our program, I manually looked and saw it was 18,360
// bytes. So, to make sure we got the right one, I do a manual check
// here.
if bytes_read != files_size {
println!(
"Unable to load program at inode {}, which should be \
{} bytes, got {}",
files_inode,
files_size,
bytes_read
);
return;
}
// Let's get this program running!
// Everything is "page" based since we're going to map pages to
// user space. So, we need to know how many program pages we
// need. Each page is 4096 bytes.
let program_pages = (bytes_read / PAGE_SIZE) + 1;
let my_pid = unsafe { NEXT_PID + 1 };
let elf_hdr;
unsafe {
NEXT_PID += 1;
// Load the ELF
elf_hdr = (buffer.get() as *const elf::Header).as_ref().unwrap();
}
if elf_hdr.magic != elf::MAGIC {
println!("ELF magic didn't match.");
return;
}
if elf_hdr.machine != elf::MACHINE_RISCV {
println!("ELF loaded is not RISC-V.");
return;
}
if elf_hdr.obj_type != elf::TYPE_EXEC {
println!("ELF is not an executable.");
return;
}
let mut my_proc =
Process { frame: zalloc(1) as *mut TrapFrame,
stack: zalloc(STACK_PAGES),
pid: my_pid,
root: zalloc(1) as *mut Table,
state: ProcessState::Running,
data: ProcessData::zero(),
sleep_until: 0,
program: zalloc(program_pages), };
// Map the program in the MMU.
let ptr = my_proc.program;
let table = unsafe { my_proc.root.as_mut().unwrap() };
unsafe {
let ph_tab = buffer.get().add(elf_hdr.phoff) as *const elf::ProgramHeader;
for i in 0..elf_hdr.phnum as usize {
let ph = ph_tab.add(i).as_ref().unwrap();
if ph.seg_type != elf::PH_SEG_TYPE_LOAD {
continue;
}
if ph.memsz == 0 {
continue;
}
memcpy(ptr.add(ph.off), buffer.get().add(ph.off), ph.memsz);
let pages = ph.memsz / PAGE_SIZE + 1;
let mut bits = EntryBits::User.val();
// This sucks, but we check each bit in the flags to see if
// we need to add it to the PH permissions.
if ph.flags & elf::PROG_EXECUTE != 0 {
bits |= EntryBits::Execute.val();
}
if ph.flags & elf::PROG_READ != 0 {
bits |= EntryBits::Read.val();
}
if ph.flags & elf::PROG_WRITE != 0 {
bits |= EntryBits::Write.val();
}
for i in 0..pages {
let vaddr = ph.vaddr + i * PAGE_SIZE;
let paddr = ptr as usize + i * PAGE_SIZE;
map(
table,
vaddr,
paddr,
bits,
0,
);
}
}
}
// This will map all of the program pages. Notice that in linker.lds in userspace
// we set the entry point address to 0x2000_0000. This is the same address as
// PROCESS_STARTING_ADDR, and they must match.
// Map the stack
let ptr = my_proc.stack as *mut u8;
for i in 0..STACK_PAGES {
let vaddr = STACK_ADDR + i * PAGE_SIZE;
let paddr = ptr as usize + i * PAGE_SIZE;
// We create the stack. We don't load a stack from the disk. This is why I don't
// need to make the stack executable.
map(
table,
vaddr,
paddr,
EntryBits::UserReadWrite.val(),
0,
);
}
// Set everything up in the trap frame
unsafe {
// The program counter is a virtual memory address and is loaded into mepc
// when we execute mret.
(*my_proc.frame).pc = elf_hdr.entry_addr;
// Stack pointer. The stack starts at the bottom and works its way up, so we have to
// set the stack pointer to the bottom.
(*my_proc.frame).regs[2] =
STACK_ADDR as usize + STACK_PAGES * PAGE_SIZE;
// USER MODE! This is how we set what'll go into mstatus when we run the process.
(*my_proc.frame).mode = CpuMode::User as usize;
(*my_proc.frame).pid = my_proc.pid as usize;
// The SATP register is used for the MMU, so we need to
// map our table into that register. The switch_to_user
// function will load .satp into the actual register
// when the time comes.
(*my_proc.frame).satp =
build_satp(
SatpMode::Sv39,
my_proc.pid as usize,
my_proc.root as usize,
);
}
// The ASID field of the SATP register is only 16-bits, and we reserved
// 0 for the kernel, even though we run the kernel in machine mode for now.
// Since we don't reuse PIDs, this means that we can only spawn 65534 processes.
satp_fence_asid(my_pid as usize);
// I took a different tact here than in process.rs. In there I created the process
// while holding onto the process list. It doesn't really matter since this is synchronous,
// but it might get dicey
if let Some(mut pl) = unsafe { PROCESS_LIST.take() } {
// As soon as we push this process on the list, it'll be schedule-able.
println!(
"Added user process to the scheduler...get \
ready for take-off!"
);
pl.push_back(my_proc);
unsafe {
PROCESS_LIST.replace(pl);
}
}
else {
println!("Unable to spawn process.");
// Since my_proc couldn't enter the process list, it
// will be dropped and all of the associated allocations
// will be deallocated.
}
println!();
}